Air Cleaner Modification to Take K&N Paper Element

This article describes a modification to the ZB oil-bath air filter unit that allows fitting a K&N  high flow filter charger elememt Part No. E-3492. (K&N Website here )

1. Remove air filter lid and oil bath element.  Air_Cleaner1

 2. Remove air filter assembly from air manifold.

3. Reverse the assembly on workbench and drill out the spot-welds holding the element inner housing to the outer casing.

4. Gently separate the 2 parts by tapping the inner housing through.

5. The next stage is to reduce the height of the inner housing to leave a 1Omm deep lip. Air_Cleaner2This will locate the K&N filter and retain strength in the remaining part of the housing. Use masking tape or a scriber to establish the circumferential line. Carefully remove the excess metal with a hacksaw fitted with a fresh HSS blade                                          

NOTE: The new filter fits neatly within the housing.

6. Deburr the cut edge of the housing and protect with Black epoxy paint to finish.

7. Reassemble the modified inner housing to the outer housing, no need to spot-weld as the unit no longer needs to retain oil.

8. Fit the new element, as easy as that. The new element comes already treated withAir_Cleaner3 K&N Filter oil ready to use.

9. The original outer casing and lid are retained.

9. No more messy oil bath cleaning or leakage.


#1 Andy Dear 2015-01-27 17:42
K&N Part No. 3492 does not exist. Should it perhaps be E-3492?
#2 test5 2015-01-27 17:45
Thanks Andrew, the K&N part number is E-3492. (Edited 20th. Oct. 2011).
#3 Andy Dear 2015-01-27 17:56
Andrew Dear 2012-10-30 17:12
I have just completed this modification and have a couple of suggestions for improvements.

When cutting down the internal baffle leave a small section adjacent to the air intake at full height. This will act as a deflector and prevent that one area of the filter element from picking up all the dust and dirt.

Secondly, I was not convinced that the lid of the air cleaner was nipping the element tightly enough to ensure a good seal. With the aid of an inspection mirror and a torch I was able to see a gap between the outer edge of the element and the lid. I believe the inner edge of the element was probably making contact with the lid but I was unable to see this.

To improve the seal I made a ring of 8mm OD neoprene tubing by gluing the ends together and cemented this into the sealing groove in the air cleaner lid. This increased the effective height of the lid by several millimetres.

The rubber ring contacts the end of the filter element centrally and when fitted, gives added confidence that the filter element is properly sealed at both ends.

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